At about 5:15 p.m. on June 17, 1971, in the Oval Office, the president ordered a crime: “I want it implemented on a thievery basis. Goddamn it, get in and get those files. Blow the safe and get it.”

The burglary he demanded was not the one that would occur exactly one year later at the Democratic National Committee’s office in the Watergate complex. Richard Nixon was ordering a break-in at the Brookings Institution, a think tank, to seize material concerning U.S. diplomacy regarding North Vietnam during the closing weeks of the 1968 presidential campaign.

As they sometimes did regarding his intemperate commands, Nixon’s aides disregarded the one concerning Brookings. But from a White House atmosphere that licensed illegality came enough of it to destroy him.

Forty years have passed since Aug. 9, 1974, when a helicopter whisked Nixon off the White House lawn, and questions remain concerning why he became complicit in criminality. Ken Hughes has a theory.

Working at the University of Virginia, in the Miller Center’s Presidential Recording Program, Hughes has studied the Nixon tapes for more than a decade. In his new book, “Chasing Shadows: The Nixon Tapes, the Chennault Affair, and the Origins of Watergate,” Hughes argues that Nixon ordered a crime in 1971 hoping to prevent public knowledge of a crime he committed in 1968.

In October 1968, Nixon’s lead over his Democratic opponent, Vice President Hubert Humphrey, was dwindling, partly because Humphrey had proposed a halt to U.S. bombing of North Vietnam. Five days before the election, President Lyndon Johnson announced the halt, hoping to convene peace talks. One impediment, however, was South Vietnam’s reluctance to participate. Its recalcitrance reflected its hope that it would be better supported by a Nixon administration.

On July 3, 1968, a Nixon campaign aide, Dick Allen, sent a memo proposing a meeting with Nixon and Anna Chennault, a Chinese-American active in Republican politics. She would bring to the meeting South Vietnam’s ambassador to Washington. The memo said the meeting must be “top secret.” Nixon wrote on the memo: “Should be but I don’t see how – with the S.S. [Secret Service].” On July 12, however, she and the ambassador did meet secretly in New York with Nixon who, she later said, designated her his “sole representative” to the Saigon government.

The National Security Agency (NSA) was reading diplomatic cables sent from South Vietnam’s Washington embassy to Saigon, where the CIA had a listening device in the office of South Vietnam’s president. The FBI was wiretapping South Vietnam’s embassy and monitoring Chennault’s movements in Washington, including her visit to that embassy on Oct. 30.

On Nov. 2 at 8:34 p.m., a teleprinter at Johnson’s ranch delivered an FBI report on the embassy wiretap: Chennault had told South Vietnam’s ambassador “she had received a message from her boss (not further identified). … She said the message was that the ambassador is to ‘hold on, we are gonna win.’” The Logan Act of 1799 makes it a crime for a private U.S. citizen, which Nixon then was, to interfere with U.S. government diplomatic negotiations.

On June 26, 1973, during the Senate Watergate hearings, Walt Rostow, who had been Johnson’s national security adviser, gave the head of the LBJ library a sealed envelope to be opened in 50 years, saying: “The file concerns the activities of Mrs. Chennault and others before and immediately after the election of 1968.” Rostow died in 2003.

Based on examination of the available evidence, Hughes concludes that Chennault was following Nixon’s directives (which Nixon denied in his 1977 interviews with David Frost). Hughes’ theory is:

June 17, 1971, was four days after The New York Times began publishing the leaked “Pentagon Papers,” the classified Defense Department history of U.S. involvement in Vietnam. Nixon worried that further leaks, including documents supposedly in a Brookings safe, would reveal his role in sabotaging negotiations that might have shortened the war. This fear caused Nixon to create the Special Investigations Unit – aka “the plumbers” – and to direct an aide to devise other proposals such as the one concerning Brookings. This aide suggested using the IRS against political adversaries, but added:

“The truth is we don’t have any reliable political friends at IRS. … We won’t be … in a position of effective leverage until such time as we have complete and total control of the top three slots at IRS.” Forty years later, the IRS has punished conservative groups, and evidence that might prove its criminality has been destroyed. Happy anniversary.

In a previous column, using data reported by an organization sponsored by the Department of Labor, I included employment figures for Oregon and several cities. Because those figures were based on the employee size of employers’ individual locations, several employers with multiple locations may not have been represented. In addition, some of those figures may not have been recently updated.

© 2014, Washington Post Writers Group